In Part 1, we began to discuss the importance of oxygen sensor voltage codes. Voltage codes can be caused by sensors that are bad and stuck lean or rich. These codes can also be caused by lean or rich running conditions. The case studies we will focus on will look at pre-cat oxygen sensor codes, both caused by parts other than the O2 sensors.
Engines have become very reliable in recent years, many reaching over 200,000 miles without major issues. As technicians, we replace a lot more ignition coils than timing chains.
While Toyota and Lexus have always been known as relatively reliable vehicles, they still suffer from ignition coil failures like any other manufacturer.